Auto-injector

Abstract

Auto-injector for administering a dose of a liquid medicament includes a housing to contain a syringe with a hollow needle and a stopper for sealing the syringe and displacing the medicament, the housing having a distal end and a proximal end with an orifice to apply against an injection site. A spring means, upon activation, can push the needle from inside the housing through the orifice and past the proximal end, operate the syringe to supply the dose of medicament, and retract the syringe with the needle after delivering the medicament. An activating means can lock the spring means in a pressurized state prior to manual operation and capable of, upon manual operation, releasing the spring means for injection.

The invention claimed is: 
     
       1. An auto-injector comprising:
 a housing; 
 a compression drive spring; 
 a plunger disposed within the housing, the plunger comprising
 a shoulder proximally offset from a distal end of the plunger with the compression drive spring disposed around the distal end of the plunger for biasing the plunger in a proximal direction relative to the housing via the shoulder of the plunger; 
 a proximal inner portion extending proximally from the shoulder of the plunger and having an inner surface that is radially inward of an outer surface of the shoulder; and 
 a proximal outer portion extending proximally from the proximal inner portion of the plunger and having a proximal end configured to engage a stopper within a syringe, the proximal outer portion being outward of the proximal inner portion; 
 
 a syringe holder disposed within the housing and configured to support the syringe, the syringe holder having a distal portion that extends radially inward and is configured to engage two opposite sides of the proximal inner portion of the plunger to limit relative movement between the plunger and the syringe holder while the syringe is supported by the syringe holder; 
 a trigger button configured to rotate relative to the housing from (i) a first button position in which the trigger button cannot be depressed towards the housing to (ii) a second button position in which the trigger button can be depressed towards the housing; and 
 an interlock sleeve rotationally coupled to the trigger button such that movement of the interlock sleeve from a first sleeve position to a second sleeve position rotates the trigger button from the first button position to the second button position, 
 wherein the auto-injector is configured such that when interlock sleeve is in the second sleeve position and the trigger button is in the second button position, depression of the trigger button towards the housing allows a resilient clip to radially deflect relative to the housing to release the plunger from being held in a distal position such that (i) the compression drive spring forces the plunger and the syringe holder in the proximal direction relative to the housing while the syringe holder and the plunger remain stationary relative to one another, and (ii) the compression drive spring forces the proximal inner portion of the plunger in the proximal direction within the syringe to proximally displace the stopper and dispense a medicament from the syringe. 
 
     
     
       2. The auto-injector of  claim 1 , wherein the auto-injector is configured such that the distal portion of the syringe holder slides along the proximal inner portion of the plunger as the stopper is proximally displaced and the medicament is dispensed from the syringe. 
     
     
       3. The auto-injector of  claim 1 , wherein the syringe holder has a proximal portion extending radially inward and being proximally spaced from the distal portion of the syringe holder, and an inner diameter of the proximal portion of the syringe holder is greater than an inner diameter of the distal portion of the syringe holder. 
     
     
       4. The auto-injector of  claim 1 , wherein the proximal inner portion of the plunger comprises one or more recessed portions of the plunger. 
     
     
       5. The auto-injector of  claim 4 , wherein the one or more recessed portions of the plunger are recessed relative to the shoulder in at least two perpendicular cross-sectional planes of the plunger. 
     
     
       6. The auto-injector of  claim 5 , wherein the one or more recessed portions of the plunger are cylindrical. 
     
     
       7. The auto-injector of  claim 5 , wherein a lateral width of the proximal inner portion is the same in each of the at least two perpendicular cross-sectional planes of the plunger. 
     
     
       8. The auto-injector of  claim 1 , wherein the distal portion of the syringe holder is configured engage the two opposite sides of the proximal inner portion of the plunger to limit relative movement between the plunger and the syringe holder without engaging an entire circumference of the proximal inner portion of the plunger. 
     
     
       9. The auto-injector of  claim 1 , wherein the distal portion of the syringe holder is configured to engage the two opposite sides of the proximal inner portion of the plunger to limit relative axial movement between the plunger and the syringe holder. 
     
     
       10. The auto-injector of  claim 1 , wherein depression of the trigger button allows the resilient clip to radially deflect relative to the housing in a radially outward direction to release the plunger from being held in the distal position. 
     
     
       11. The auto-injector of  claim 1 , wherein the auto-injector is configured such that when the plunger proximally advances within the housing the syringe holder proximally moves from (i) a first syringe holder position in which a proximal end of a needle of the syringe is distal to a proximal end of the housing to (ii) a second syringe holder position in which the proximal end of the needle of the syringe is proximal to the proximal end of the housing. 
     
     
       12. The auto-injector of  claim 1 , wherein the auto-injector is configured such that the plunger slides through an opening at the distal portion of the syringe holder when the plunger proximally advances within the housing, and the opening extends axially through the syringe holder. 
     
     
       13. An auto-injector comprising:
 a housing; 
 a compression drive spring; 
 a plunger disposed within the housing, the plunger comprising
 a shoulder proximally offset from a distal end of the plunger with the compression drive spring disposed around the distal end of the plunger for biasing the plunger in a proximal direction relative to the housing via the shoulder of the plunger; 
 a proximal inner portion extending proximally from the shoulder of the plunger and having an inner surface that is radially inward of an outer surface of the shoulder; and 
 a proximal outer portion extending proximally from the proximal inner portion of the plunger and having a proximal end configured to engage a stopper within a syringe, the proximal outer portion being outward of the proximal inner portion; 
 
 a syringe holder disposed within the housing and configured to support the syringe, the syringe holder having a distal portion that extends radially inward and is configured to engage two opposite sides of the proximal inner portion of the plunger to limit relative movement between the plunger and the syringe holder; 
 a button configured to rotate relative to the housing from (i) a first button position in which the button cannot be depressed towards the housing to (ii) a second button position in which the button can be depressed towards the housing; and 
 a sleeve rotationally coupled to the button such that movement of the sleeve from a first sleeve position to a second sleeve position rotates the button from the first button position to the second button position. 
 
     
     
       14. The auto-injector of  claim 13 , wherein the auto-injector is configured such that when the sleeve is in the second sleeve position and the button is in the second button position, depression of the button towards the housing allows the plunger to be released from being held in a distal position against a biasing force of the compression drive spring. 
     
     
       15. The auto-injector of  claim 14 , wherein depression of the button towards the housing allows a resilient clip to radially deflect relative to the housing to release the plunger from being held in the distal position. 
     
     
       16. The auto-injector of  claim 14 , wherein after the plunger is released from being held in the distal position, the compression drive spring forces the plunger and the syringe holder to move in the proximal direction relative to the housing while the distal portion of the syringe holder and the plunger remain stationary relative to one another. 
     
     
       17. The auto-injector of  claim 14 , wherein after the plunger and the syringe holder move in the proximal direction relative to the housing the compression drive spring forces the stopper to move in the proximal direction relative to the housing by an engagement between the proximal outer portion of the plunger and the stopper to dispense a medicament from the syringe. 
     
     
       18. The auto-injector of  claim 13 , wherein the auto-injector is configured such that the plunger is axially spaced from the stopper before the button is depressed towards the housing. 
     
     
       19. The auto-injector of  claim 13 , comprising the syringe, the syringe containing a medicament, and the auto-injector being configured to dispense the medicament from the syringe when the button is depressed towards the housing. 
     
     
       20. The auto-injector of  claim 13 , wherein the auto-injector is configured such that a majority of an axial length of the proximal outer portion of the plunger is disposed within a barrel of the syringe before the button is depressed towards the housing. 
     
     
       21. The auto-injector of  claim 20 , wherein the axial length of the proximal outer portion of the plunger is greater than an axial length of the stopper within the syringe. 
     
     
       22. An auto-injector comprising:
 a housing; 
 a compression drive spring; 
 a plunger disposed within the housing, the plunger comprising
 a shoulder proximally offset from a distal end of the plunger with the compression drive spring being disposed around the distal end of the plunger for biasing the shoulder in a proximal direction relative to the housing; and 
 a proximally-extending portion extending proximally from the shoulder of the plunger to a proximal end of the plunger, the proximally-extending portion having an outer surface that is radially inward of the shoulder, the proximal end of the proximally-extending portion being configured to engage a stopper within a syringe; 
 
 a syringe holder disposed within the housing and configured to support the syringe, the syringe holder having a distal portion that extends radially inward and is configured to engage two opposite sides of the proximally-extending portion of the plunger to limit relative movement between the plunger and the syringe holder before a medicament is dispensed from the auto-injector; 
 a button configured to rotate relative to the housing from a first button position to a second button position to allow the button to be depressed towards the housing; and 
 a sleeve rotationally coupled to the button such that movement of the sleeve from a sleeve position to a second sleeve position rotates the button from the first button position to the second button position. 
 
     
     
       23. The auto-injector of  claim 22 , wherein one or more portions of the housing are cylindrical. 
     
     
       24. The auto-injector of  claim 23 , wherein at least one portion of the housing is not cylindrical. 
     
     
       25. The auto-injector of  claim 22 , wherein the proximally-extending portion of the plunger comprises one or more recesses for engaging the syringe holder to limit relative movement between the plunger and the syringe holder. 
     
     
       26. An auto-injector comprising:
 a housing; 
 a syringe containing a medicament; 
 a plunger disposed within the housing, the plunger comprising a proximally-extending portion configured to engage a stopper within the syringe; 
 a syringe holder disposed within the housing and configured to support the syringe, a distal portion of the syringe holder extending radially inward and being configured to engage two opposite sides of the proximally-extending portion of the plunger to limit relative movement between the plunger and the syringe holder before the medicament is dispensed from the auto-injector; 
 a button configured to rotate relative to the housing to allow a user to depress the button for allowing the medicament to be dispensed from the auto-injector; and 
 a first sleeve rotationally coupled to the button such that movement of the first sleeve from a first sleeve position to a second sleeve position rotates the button relative to the housing to allow the user to depress the button. 
 
     
     
       27. The auto-injector of  claim 26 , comprising a second sleeve configured to move distally within the housing and force the syringe holder in a distal direction relative to the housing for needle retraction after the medicament has been dispensed from the syringe. 
     
     
       28. The auto-injector of  claim 26 , wherein the medicament is a GLP-1 class medicament. 
     
     
       29. The auto-injector of  claim 26 , wherein depression of the button allows a resilient clip to radially deflect relative to the housing in a radial direction to release the plunger from being held in a distal position for needle insertion and medicament delivery. 
     
     
       30. The auto-injector of  claim 22 , wherein the sleeve is a first sleeve, and the auto-injector comprises a second sleeve configured to move distally within the housing and force the syringe holder in a distal direction relative to the housing for needle retraction after the medicament has been dispensed from the syringe.